1. Field of the Invention
The present invention relates to a thin film magnetic head used in a magnetic recording and reproducing apparatus such as a hard disk device and a magnetic tape device and having effects in high density recording, its manufacturing method, and a magnetic recording and reproducing apparatus mounting such thin film magnetic head.
2. Description of the Related Art
Hitherto, in a magnetic recording and reproducing apparatus, using an inductive type recording head, signals are recorded in a magnetic recording medium such as magnetic tape or magnetic disk, and the signals recorded in the magnetic recording medium are detected by using a magneto-resistive type (MR type) reproducing head.
In a magnetic recording and reproducing apparatus where high-density recording is required, the recording head and reproducing head are separately composed in order to optimize the recording efficiency and reproducing capacity. For example, in a hard disk device, a so-called thin film magnetic head integrally forming the inductive type recording head and MR type reproducing head or GMR type reproducing head as shown in FIG. 15 and FIG. 16 is used.
A conventional thin film magnetic head is explained by referring to the drawings.
FIG. 15 is a front schematic view showing an air bearing surface (ABS) of a conventional thin film magnetic head with a recording medium, and FIG. 16 is a top view of the conventional thin film magnetic head.
As shown in FIG. 15, a recording head 150 of this thin film magnetic head is composed of an upper magnetic core 151, a recording gap 152, a lower magnetic core 153 disposed adjacent the recording gap 152, and a coil winding 164 (see FIG. 16). The lower magnetic core 153 is also called a common shield because it has also a shielding function for the reproducing head. Herein, the width 154 of the portion confronting the common shield of the upper magnetic core 151 defines the mechanical recording track width.
A reproducing head 159 is composed of the common shield 153 and a lower magnetic shield 157 which are disposed adjacent a reproducing gap 158, and an MR element 156 disposed between the shields 153 and 157.
FIG. 17 shows a state of the recording magnetic field generated around the recording gap 152, and a recording track width 171 is formed by the recording magnetic field. Due to the recording magnetic field leaking at both ends of the recording gap 152, a recording region 171 where information is recorded on a magnetic recording medium spreads wider than the mechanical track width 172 of the magnetic core 151. The region 173 in the recording magnetic field spreading wider than the mechanical track width is called a recording fringe. As mentioned above, the recording track width 171 is composed of the recording fringes 173 formed at both sides of the recording gap 152, and a normal recording region 172. On the other hand, the reproducing track width 155 (see FIG. 15) is generally formed smaller than the recording track width 171 in order to maintain an off-track margin.
The magnetic field strength of recording fringe 173 is weaker than that of the normal recording region 172, and is different in the demagnetization field components in the recording medium as compared with the normal recording region 172, and therefore the recording phases are different, and the noise components are larger.
An example of calculation of recording magnetic field occurring around the recording gap 152 in the composition in FIG. 17 is shown in FIG. 18. Herein, the x-direction is the gap width direction, the y-direction is the gap length direction, and the z-direction shows the intensity of the recording magnetic field. The swell of the recording magnetic field due to recording fringe is shown in parts 181 and 182 in the diagram.
In a conventional magnetic head, it has been attempted to join the butt ends of the recording gap in order to reduce the recording fringe in the width direction of the recording gap. For example, in a head for VTR, in order to eliminate butt end deviation, a trimming method wherein magnetic cores of the vicinity of the gap 191 are trimmed in shape 192 has been proposed as shown in FIG. 19 (for example, Micro-Machining of Magnetic Metal Film Using Electro-discharge Technique. Y. Honma, International Conference of Micromechanics for Information, PP.318, 1997).
In the thin film magnetic head for HDD, a shape is proposed as shown in FIG. 20, in which a protrusion 203 is formed on a common shield 202 having a greater width than an upper magnetic core 201 by trimming. (For example, see Kiyono, xe2x80x9cEffects of writing magnetic pole trimming in merge type MR head,xe2x80x9d Lectures at 22nd Meeting of Japan Society of Applied Magnetism, p. 202, 1998.)
Generally, penetration distance of the magnetic field leaking from the recording gap is equal to or less than the xc2xd height of the gap width. Therefore, if attempted to reduce the fringe by a technique of joining the butt ends of the recording gap, the recording fringe in the recording magnetic field shown in FIG. 17 expanded by the portion of gap width at maximum. Therefore, in order to record at higher density, it was required to reduce the recording track width further and curtail the recording fringe amount substantially at the same time.
The invention therefore provides a thin film magnetic head constituted by integrally forming an inductive recording head composed of a common shield serving commonly as upper magnetic core and lower magnetic core disposed adjacent a recording gap, and a coil winding, and a reproducing head composed of MR elements disposed between the common shield and lower magnetic shield, and the both magnetic shields, in which a shunt member made of a soft magnetic material is provided near the recording gap of the recording head.
This configuration presents a thin film magnetic head capable of suppressing leak magnetic field generated at the recording gap, decreasing the recording fringe substantially, narrowing the track in the recording head, and enhancing the recording track density, and a method of manufacturing the same.